Automatic systems for controlling lateral tilt and height of headers on a variety of agricultural machines and vehicles, particularly harvesting machines such as combines and windrowers, are well known. Such known systems typically utilize an electro-hydraulic or mechanical apparatus for controlling the lateral tilt, to maintain a desired uniform distance between the header and a ground surface therebelow without action by the operator.
As a representative example, some known systems utilize a mechanical linkage incorporating gauge wheels or skids. The gauge wheels or skids are set a fixed distance below the header cutting or gathering surface and the header is lowered to bring the wheels or skids into contact with the ground, allowing them to carry a portion of the header weight. Ground elevation changes are followed by the gauge wheels to raise and lower the ends of the header relative to the harvesting vehicle to maintain the uniform cut height.
Other known systems fix the header to the harvesting vehicle and rely on a lifting and tilting device on the vehicle and sensors in connection with a controller to control height and lateral tilt to maintain uniform cut height. However, these have been observed to have performance limitations at higher travel speeds and when used with wider headers, particularly response lag.
Still other known systems for controlling header height use changes in pressures to maintain uniform cut height. This type of system relies on some portion of the header weight to be carried by the ground. When the header bottom contacts an obstruction, if the terrain rises, or the ground carries more of the header weight, pressures in the lift circuit are lowered, which causes the control circuit to lift the header. However, the known systems of this type do not account for lateral tilting of the header.
An observed shortcoming of the known lateral tilt controls is slow response to changing terrain conditions at higher travel speeds when used on wider headers.
Therefore, what is sought is a manner of automatic lateral tilt control for headers of agricultural vehicles, particularly harvesting machines, which provides an accurate and responsive ability to maintain uniform cut height, particularly at high travel speeds and for wider headers.